var imgShow={
	WIDTH:400,
	HEIGHT:400,
	maskW:100,
	maskH:100
}
function maskMove(e){
	var l=e.offsetX;
	var t=e.offsetY;
	var img=largeMask.querySelector("img");
	var imgx=parseFloat(img.clientWidth)-imgShow.WIDTH;
	var imgy=parseFloat(img.clientHeight)-imgShow.HEIGHT;
	var x=imgShow.WIDTH-imgShow.maskW;
	var y=imgShow.HEIGHT-imgShow.maskH;
	if(l>=imgShow.maskW/2&&l<=imgShow.WIDTH-imgShow.maskW/2){
		mask.style.left=l-imgShow.maskW/2+'px';
		img.style.left=(-l+imgShow.maskW/2)/x*imgx+'px';
	}
	if(t>=imgShow.maskH/2&&t<=imgShow.HEIGHT-imgShow.maskH/2){
		mask.style.top=t-imgShow.maskH/2+'px';
		img.style.top=(-t+imgShow.maskH/2)/y*imgy+'px';
	}
}
function maskOver(){
	mask.style.display='block';
	largeMask.style.display='block';
}
supMask.addEventListener('mouseover',function(){
	maskOver();
	supMask.addEventListener('mousemove',maskMove);
});
supMask.addEventListener('mouseout',function(e){
	mask.style.display='none';
	largeMask.style.display='none';
});
